Fragment Backstack Recycling and Movement

activity.java

public class Activity extends AppCompatActivity {

    public String lastFragment;
    private FragmentManager fragmentManager;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_onboarding);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        fragmentManager = getSupportFragmentManager();


        actionBar = getSupportActionBar();
        if (actionBar != null) {
            actionBar.setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);
            actionBar.setCustomView(R.layout.action_bar_kudolife);
            header = (MulticoloreTextView) findViewById(R.id.title);
        }

    public void nextFragment(Fragment fragment, String newTag, String curTag) {

        lastFragment = curTag; //Tracks back location

        Fragment check = checkForFragment(newTag);
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

        if (check != null) {
            fragment = check; //Fragment exists
        } else {
            fragmentTransaction.addToBackStack(newTag); //Fragment doesn't exist
        }

        fragmentTransaction.replace(R.id.parent, fragment, newTag);
        fragmentTransaction.commit();

    }


    @Override
    public void onBackPressed() {

        int i = fragmentManager.getBackStackEntryCount() - 1;

        for (int j = i; j >= 0; j--) {

            FragmentManager.BackStackEntry entry = fragmentManager.getBackStackEntryAt(j);
            String tag = entry.getName();

            if (lastFragment.equals(tag)) {

                Fragment fragment = fragmentManager.findFragmentByTag(tag);

                FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
                fragmentTransaction.replace(R.id.parent, fragment, tag);
                fragmentTransaction.commit();

                if (j != 0) {
                    entry = fragmentManager.getBackStackEntryAt(j - 1);
                    lastFragment = entry.getName();

                } else {
                    lastFragment = "END OF STACK, NOTHING TO RETURN";
                }

                return;
            }
        }
    }

}